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2 Injured in Walnut Creek Apartment Blast, Fire

An explosion, fire and "multiple injuries" were reported at a four-unit apartment building in Walnut Creek Friday morning, sending crews to battle flames and two people to the hospital in critical condition. Christie Smith reports. (Published Friday, Oct. 31, 2014)

A powerful blast and two-alarm blaze that tore through a Walnut Creek apartment building Friday morning, critically burning two people and causing its roof to collapse, resulted from a marijuana and
hash oil drug extraction manufacturing process, police said.

"It was an incredible explosion, one I've never seen before," said Bob Grossman, who lives a block away from the six-unit building at 1564 Sunnyvale Avenue. "It shook our windows, and knocked over our windows."

The blast was reported just after 10 a.m. and sent two male burn victims to the hospital with critical burns, Contra Costa County Fire Protection Service Capt. Kent Kirby said.

Initially, Kirby said one person might be unaccounted, but he said later a search turned up nothing.

Photos: Walnut Creek Apartment Building Explosion

Officials said during the initial investigation after the blaze they found burned and exploded butane canisters, which clued them to a possible hash oil lab.

"We have strong evidence that what resulted in the fire, the injuries and the explosion was a butane hash oil extraction process," fire investigator Vic Massenkoff said. The volatile process uses butane as a solvent to "take out THC, the active ingredient in marijuana, into a very concentrated form."

“The serious danger is that, as they’re using this butane, raw butane vapors are spewing out into the room they’re in,” Massenkoff said. “Butane vapors are like gasoline vapors. They’re heavier than air; they sink to the ground and look for an ignition source. Something as simple as a spark of static electricity can ignite butane vapors.”